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demitau
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What is known about fine stability properties of ODEs of the following kind? $$ \dot{x} = Ax + b + \phi(x),\quad x\in \mathbb{R}^d ,$$ where $d\geq 1$; $A$ is a constant matrix with all e.v. having real part $<0$; $b$ is a constant vector and $\phi:\mathbb{R}^d\to \mathbb{R}^d_{\geq 0}$ is a function, growing faster than linear on $+\infty$. A particular $\phi$ to think about is $\phi(x) = c\exp(x)$, for a fixed $c>0$ and $\exp(x)$ means coordinate-wise application of the exponential.

For example, for $d=1$ it is easy to see that there is a stable fixed point $x_s$, which is followed by an unstable one $x_u>x_s$, after which each solution goes to infinity. I would like to find out whether there are some qualitative differences in higher dimensions. A dream result would be a detailed description of the attraction basin for the stable fixed point.

UPD: It is not true even in 1D that there is always a stable point. But one can always derive conditions for its existence by looking at how many solutions does equation $Ax+b+\phi(x) = 0$ have and calculating derivatives at the roots.

Are there some classical (or not so) references covering this kind of equations?

What is known about fine stability properties of ODEs of the following kind? $$ \dot{x} = Ax + b + \phi(x),\quad x\in \mathbb{R}^d ,$$ where $d\geq 1$; $A$ is a constant matrix with all e.v. having real part $<0$; $b$ is a constant vector and $\phi:\mathbb{R}^d\to \mathbb{R}^d_{\geq 0}$ is a function, growing faster than linear on $+\infty$. A particular $\phi$ to think about is $\phi(x) = c\exp(x)$, for a fixed $c>0$ and $\exp(x)$ means coordinate-wise application of the exponential.

For example, for $d=1$ it is easy to see that there is a stable fixed point $x_s$, which is followed by an unstable one $x_u>x_s$, after which each solution goes to infinity. I would like to find out whether there are some qualitative differences in higher dimensions. A dream result would be a detailed description of the attraction basin for the stable fixed point.

Are there some classical (or not so) references covering this kind of equations?

What is known about fine stability properties of ODEs of the following kind? $$ \dot{x} = Ax + b + \phi(x),\quad x\in \mathbb{R}^d ,$$ where $d\geq 1$; $A$ is a constant matrix with all e.v. having real part $<0$; $b$ is a constant vector and $\phi:\mathbb{R}^d\to \mathbb{R}^d_{\geq 0}$ is a function, growing faster than linear on $+\infty$. A particular $\phi$ to think about is $\phi(x) = c\exp(x)$, for a fixed $c>0$ and $\exp(x)$ means coordinate-wise application of the exponential.

For example, for $d=1$ it is easy to see that there is a stable fixed point $x_s$, which is followed by an unstable one $x_u>x_s$, after which each solution goes to infinity. I would like to find out whether there are some qualitative differences in higher dimensions. A dream result would be a detailed description of the attraction basin for the stable fixed point.

UPD: It is not true even in 1D that there is always a stable point. But one can always derive conditions for its existence by looking at how many solutions does equation $Ax+b+\phi(x) = 0$ have and calculating derivatives at the roots.

Are there some classical (or not so) references covering this kind of equations?

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demitau
  • 225
  • 1
  • 7

Stability of ODEs with exponentials in the vector field

What is known about fine stability properties of ODEs of the following kind? $$ \dot{x} = Ax + b + \phi(x),\quad x\in \mathbb{R}^d ,$$ where $d\geq 1$; $A$ is a constant matrix with all e.v. having real part $<0$; $b$ is a constant vector and $\phi:\mathbb{R}^d\to \mathbb{R}^d_{\geq 0}$ is a function, growing faster than linear on $+\infty$. A particular $\phi$ to think about is $\phi(x) = c\exp(x)$, for a fixed $c>0$ and $\exp(x)$ means coordinate-wise application of the exponential.

For example, for $d=1$ it is easy to see that there is a stable fixed point $x_s$, which is followed by an unstable one $x_u>x_s$, after which each solution goes to infinity. I would like to find out whether there are some qualitative differences in higher dimensions. A dream result would be a detailed description of the attraction basin for the stable fixed point.

Are there some classical (or not so) references covering this kind of equations?